Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
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B
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
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C
Assertion is correct but Reason is incorrect
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D
Assertion is incorrect but Reason is correct
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Solution
The correct option is B Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion A=⎡⎢⎣0c−b−c0ab−a0⎤⎥⎦ ⇒(tI−A)=⎡⎢⎣t−cbct−a−bat⎤⎥⎦ adj(tI−A)=⎡⎢⎣t2+a2tc+abac−tbtc−abt2+b2at+bcac+tb−at+bct2+c2⎤⎥⎦ =t2⎡⎢⎣100010001⎤⎥⎦+t⎡⎢⎣0c−b−c0ab−a0⎤⎥⎦+⎡⎢⎣−c2−b2abacab−c2−a2bcacbc−b2−a2⎤⎥⎦+(a2+b2+c2)⎡⎢⎣100010001⎤⎥⎦ ∴adj(tI−A)=t2I+tA+A2+(a2+b2+c2)I Assertion is true. adjA=⎡⎢⎣a2abacabb2bcacbcc2⎤⎥⎦ =⎡⎢⎣−c2−b2abacab−c2−a2bcacbc−b2−a2⎤⎥⎦+(a2+b2+c2)⎡⎢⎣100010001⎤⎥⎦ ∴adjA=A2+(a2+b2+c2)I Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.